This invention relates to a semiconductor arrangement with an image recording unit comprising an infra-red-sensitive compound semiconductor material and having an integrated semiconductor circuit as a read out unit, the two units being connected both electrically and mechanically and a method for manufacturing this semi conductor arrangement.
Infra-red-Quantum-Detectors are produced from semiconductor material in which the radiation interacts with electrons from the lattice bond. This interaction may take the form of ionisation of donors or acceptors (extrinsic detectors) or stimulation of electrons from the valence band into the conduction band (intrinsic detectors). In-doped silicon, for example, for the wave length range betwen 3 and 5 .mu.m and Ga-doped silicon for the wave length range of 8 to 12 .mu.m belong to the class known as extrinsic detectors. Mercury/Cadmium/Telluride for example belongs to the class known as intrinsic detectors and is suitable, depending on its composition (the concentration of cadmium/telluride) for the wave length range between 3 and 5 .mu.m and 18 and 14 .mu.m.
In addition, intrinsic detectors have the advantage that they can be operated at relatively high temperatures, for example at temperatures greater than or equal to that of liquid nitrogen; and that because of their higher absorption coefficient they can be made thinner, for example, less than or equal to 10 .mu.m, and therefore have more sharply contoured sensitive surfaces.
On the other hand, extrinsic detectors based on silicon have the advantage that part of the signal processing can be integrated simply into the detector mosaic and the number of signal output lines can be reduced by means of charge shift registers (CCD) or charge injection (CID).
If the infra-red detector is to be used to display an image without an optical scanning system, then it is desirable to have a high density of detector elements, for example more than 64.times.64 elements on the focal plane. In this case integration of the read-out circuits is indispensable. In order to maintain the advantages of the intrinsic detector material HgCdTe, two methods have been tried.
The first is to integrate the read-out unit into the HgCdTe-material. This has been described for example in "Infrared Monolithic HgCdTe IR CCD Focal Plane Technology", D. D. Buss et al, Intern. Electron. Devices Meeting, Washington DC, 1978.
In the case of highly integrated circuits in narrow band semiconductors such as HgCdTe, considerable physical and technological difficulties are involved.
The second method consists of connecting HgCdTe-detectors by means of a simultaneous soldering process to Si-readout circuits. A metalic contact on the HgCdTe-body and a corresponding contact on the Si-circuit are associated with each detector element in the HgCdTe-semiconductor body which includes the whole of the detector. The two semiconductor bodies are combined in similar manner to flip chip techniques and the associated contacts are soldered together. This is described for example in: "Infrared Focal Planes in Intrinsic Semiconductors", J. T. Longo et al, IEEE Trans. Electr. Dev. ED 25, page 213 232 (1978).
The output of this type of simultaneous soldering process is therefore limited. In addition there are considerable technological difficulties with this method.